Veusz is mostly written in Python, designed to be compatible with Python 2.6+ and Python 3.3+. C++ is used to optimize the drawing code. Veusz uses the numpy library for numerics and Qt/PyQt4 for the user interface. Veusz is not based on matplotlib, except for the library used for contouring. The program is licenced under the GPL (version 2 or greater).
The main developer for Veusz is Jeremy Sanders. Veusz's source code repository is hosted on github. Please report bugs, feature suggestions and any changes you are working on in the issue tracker. The Veusz subreddit can also be used for discussion about changes.
Useful information for getting started with Veusz development can be found on the wiki.